As the method of producing a mandelonitrile compound, for example, JP-A No. 7-33727 describes a method which comprises reacting a benzaldehyde compound and hydrogen cyanide in the presence of an alkali metal salt in a water solvent. Further, JP-A No. 2005-232105 discloses a method which comprises reacting a benzaldehyde compound and hydrogen cyanide in the presence of sodium carbonate or sodium acetate in a water solvent.